libxslt: add licensing information

Signed-off-by: Jiri Slachta <slachta@cesnet.cz>
tiff: add licensing information

Signed-off-by: Jiri Slachta <slachta@cesnet.cz>
libssh2: add licensing information

Signed-off-by: Jiri Slachta <slachta@cesnet.cz>